The magnetization study of melt-spun ribbons of B containing TbFe ₂ alloys

We have carried out the magnetization study of melt-spun ribbons of (Tb_0.33Fe_0.67)_1-xB_x (x=0, 0.02, 0.05, 0.1, and 0.15) alloys. The temperature dependence of magnetization was measured using a superconducting quantum interference device and a vibrating-sample magnetometer during heating from 5 to 800 K, with an applied field of either 10 or 50 kOe. The present study shows the existence of noncollinear magnetics structures. From an analysis of the approach to saturation magnetization, the average magnetic moment μ_a, random anisotropy field H_r, and local random anisotropy constant K _L have been extracted. It is found that μ_a decreases from 1.68 (x=0) to 1.33 μ_B (x=0.15) and K_L increases with increasing B concentration. This result suggests that the addition of B seems to increase the random anisotropy and hence to decrease the magnetic order, resulting a sperimagnet with large spread angle.